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Japan quake tsunami links and notes

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Japan's quake more powerful than first estimate

New estimates by the US Geological Survey suggest that the earthquake that struck Japan on 2011 March 11 was magnitude 9.0. Grpahic from New Scientist.

The Mainichi Daily News has reported that the strongest recorded earthquake to hit Japan rocked the northeastern coast Friday, triggering a series of tsunami including a 10-meter wall of water that submerged residential areas and farms with muddy streams and washed away scores of people, vehicles, boats and a storage tank on fields and ports in northeastern Japan.

The 10-meter tsunami was observed at Sendai port in Sendai, Miyagi Prefecture at around 3:55 p.m. after the quake with a magnitude of 8.8 rocked the region, local police said. A tsunami expert at the government-affiliated Port and Airport Research Institute described the tsunami following the 2:46 p.m. quake as “one of the highest and widest in terms of areas of devastation in the nation’s history.” Shigeo Takahashi, senior researcher at the institute, said, “It’s a tsunami of a once-in-a-century scale.”

The New Scientist noted that the Japanese earthquake has triggered a series of tsunami waves that are now moving east across the Pacific. How will the countries they hit be affected? The shape of each landmass is a major factor determining how the tsunami behaves. Tsunamis are most dangerous when they run over a large area of shallow water. This causes the first wavefront to slow down, so successive waves pile up to form one tremendous wave.

As a result small Pacific islands, especially ones that lie in otherwise deep water, should be largely unaffected. Wave height here might reach 30 centimetres at most. “A little atoll presents a pencil in the water, and the wave just goes right past,” says Robert Cessaro, a senior geophysicist at the Pacific Tsunami Warning Center (PTWC) in Hawaii. Because most of the islands in the tsunami’s path are fairly small, they should see waves 10 to 30 centimetres high at most.

Written by makanaka

March 11, 2011 at 23:33

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